1. Field
The present teachings relate to power supplies in integrated devices. More particularly, the present teachings relate to a dual supply override, such as a dual supply override in integrated devices without requirement for extra enable/disable pins.
2. Description of Related Art
An integrated circuit (IC) typically requires multiple power supplies to drive its internal functional circuitry. In some cases the entirety of these supplies can be generated externally from the IC and be fed through dedicated pins to the IC when the IC gets integrated into the final product. In other cases, the IC gets integrated into products which are powered by a single source (e.g. battery in a cellular phone) and thus the IC needs to generate its own internal power supplies using the available single supply. These supplies typically include one positive supply (Vdd) and one negative supply (Vss) with reference to some fixed reference potential (Vref, e.g. ground). Chip manufacturers need to cater to both of these cases and oftentimes are required to fabricate different versions of the same IC (e.g. with same functional circuitry), but with different input power pins and different internal power supply generation circuitry.
As used in the present disclosure, the term “IC” can refer to an integrated circuit or monolithic integrated circuit composed of a set of electronic circuits on one small plate (“chip”) of semiconductor material such as silicon. An IC can also be referred to as a “chip” or a “microchip”. The set of electronic circuits within an IC are typically made of a very large number of transistors and other electronic components, which may need supply power (e.g. positive supply and negative supply) to operate. Based on the number of electronic components used within the IC and the size of the plate, thus the density of electronic components within the IC, ICs can be further categorized in, for example, small-scale integration (SSI), medium-scale integration (MSI), large-scale integration (LSI), and very-large-scale integration (VLSI). Newer categories also include wafer-scale integration (WSI), system-on-a-chip (SoC) and three-dimensional integrated circuits (3D-IC). Microprocessors or intelligent ICs, also known as “cores”, and digital memory chips are some examples of ICs.